Machine for cutting or stripping pavement

ABSTRACT

A machine for removing pavement by cutting or stripping away the pavement on a highway in connection with highway-repair operations. The apparatus includes a vehicle which has a suitable tool driven to cut or strip away the pavement from the surface of the highway. Since in many cases it is necessary to initially heat the pavement to prepare it for removal, the vehicle has operatively connected to its front end a frame which carries sources of radiant heat from which heat is directed down to the pvavment to heat the latter in preparation for removal thereof. This frame is made up of sections connected to each other in such a way that the frame can be collapsed to a location carried by the front end of the vehicle so that the latter can travel without being hampered by riding of the frame and heating structure on the highway. The sections can be expanded from their inoperative position carried by the vehicle to an operative position extending forwardly from the vehicle so as to render the heating structure operative. The heating structure provides the radiant heat energy from a combustible gas which if it is derived from a tank carried by the vehicle in which the gas is in liquified form is first converted into dry gaseous form by a suitable vaporizer situated between the tank of liquified gas and the heating structure.

United States Patent [191 Wirtgen [111 3,822,956 [451 July 9,1974

[ MACHINE FOR CUTTING OR STRIPPING PAVEMENT [76] Inventor: Reinhard Wirtgen, Hohnerstrasse 5461, Windhagen uber Linz, Rhine, Germany [22] Filed: Mar. 5, 1973 [21] Appl. No.: 338,049

[30] Foreign Application Priority Data Primary Examiner-Nile C. Byers, Jr. Attorney, Agent, or Firm-Steinberg & Blake [5 7] ABSTRACT A machine for removing pavement by cutting or stripping away the pavement on a highway in connection with highway-repair operations. The apparatus includes a vehicle which has a suitable tool driven to cut or strip away the pavement from the surface of the highway. Since in many cases it is necessary to initially heat the pavement to prepare it for removal, the vehicle has operatively connected to its front end a frame which carries sources of radiant heat from which heat is directed down to the pvavment to heat the latter in preparation for removal thereof. This frame is made up of sections connected to each other in such a way that the frame can be collapsed to a location carried by the front end of the vehicle so that the latter can travel without being hampered by riding of the frame and heating structure on the highway. The sections can be expanded from their inoperative position carried by the vehicle to an operative position extending forwardly from the vehicle so as to render the heating structure operativei The heating structure provides the radiant heat energy from a combustible gas which if it is derived from a tank carried by the vehicle in which the gas is in liquified form is first converted into dry gaseous form by a suitable vaporizer situated between the tank of liquified gas and the heating structure.

40 Claims, 6 Drawing Figures PAIENI JUL 9l974 sum 2 0F 5 PATENTEDJUL 9.974

SHEET S' [If 5 PATENTED 9' SHEET 5 OF 5 MACHINE FOR CUTTING OR STRIPPING PAVEMENT BACKGROUND OF THE INVENTION The invention relates to a machine for cutting or stripping pavement with a chassis which preferably has its own driving engine and which carries a cutting or stripping device and with a heating device for heating the pavement.

In order to repair highway surfaces which are damaged by spiked tires, frost upheavels or other effects of vehicles and weather influence, it is known to cut or strip away large areas and then to provide a new covering. Particularly with respect to stripping away of pavement, as well as to an increasing extent with cutting away of highway surfaces, as is required by use of highway surfaces which are always becoming more wear resistant and harder, the pavement which is to be removed is heated and only then is it cut or stripped away. In order to heat the pavement which is to be removed there are known heating devices which are made of a fixed frame having a width corresponding to the width of the cutting or stripping device and a length of a few meters, a number of heating elements being arranged on this frame and having a construction depending upon the source of energy which is used.

This fixed frame has several supporting wheels by which it is capable of being supported on the highway surface, and it is constructed at its end which is situated at the front end of the vehicle chassis in such a way that at the beginning of the cutting operation it is fixed to the vehicle chassis of the apparatus and at the end of the cutting operation it is disconnected therefrom and after being loaded upon a truck is transported to another operating location. Such operations are clearly of considerable inconvenience and time consuming and require the use of additional transporting means. In addition, beside requiring workers for loading and unloading the heating structure onto and off from a truck, skilled operators are required for properly making the connections between the energy source and the heating elements. This results in undesirably high setting-up costs.

With the known devices it is preferred to use a heating gas to heat the pavement which is to be removed, and the heating elements therefore consist, for example, either of pipes provided with radial bores, which communicate by feed pipes or hoses with each other and with a gas tank, or they'consist of many individual flame jets which communicate with each other and with the gas tanks by way of a system of pipes. These heating devices can be operated with liquified gas or with dry gas, although the use of liquified gas is preferred for economic reasons. The gas which is required to operate the heating devices is situated in a number of gas tanks which are arranged at the rear part of the heating structure or on the front part of the chassis of the machine. The gas tanks are in general connected with a primary pipe which is connected to the heating structure and can be placed in communication with the heating structure either all at once or one after the other by corresponding control of their valves. In order to convert the liquified gas taken from the gas tanks into a combustible dry gas a vaporizing pipe coil is situated before each gas discharging nozzle of the heating device, and the end of this pipe coil which is connected to the nozzle is directed first upwardly and then downwardly to the nozzle.

These known heating devices, however, have considerable disadvantages. Thus, the arrangement of such pipe coils at each gas discharge nozzle has an extremely undesirable effect on the manufacturing costs of the heating device. In addition, and this is of particular importance, the exchange of an empty gas tank for a full one requires a large amount of time and involves operations which have high labor costs. Thus, for the purpose of exchanging a heavy gas tank at least two workers and under certain circumstances a vehicle provided with a crane are required, in order to take the empty gas tank from the heating device or from the chassis of the machine and load it on to a truck and to load a full gas tank from the truck onto the heating device or chassis of the machine.

Before and after the loading operations, it is necessary to disconnect and handle a number of connections, with the use of suitable tools, which'correspond to the number of gas tanks. In addition, it is necessary to stop the operation of the machine during the exchange of gas tanks, which has an extremely unfavorable effect on the extent to which the machine is used, particularly when the machines are operated in shifts. A further considerable disadvantage of the known heating devices resides in the fact that gas losses are relatively high because of the many and frequent manipulations of the connections. Of course, such leakage losses can be reduced to a neglibible amount by properly closing the connections after each actuation thereof, which is to say after each exchange of a gas tank, but as a rule the costs involved in the latter operations are higher than those resulting from leakage losses.

A further problem is created by the vaporizer for converting the liquified gas discharged from a gas tank or any other supply container to a combustible dry gas which, for example, is contained in a pipe coil heated by gas and connected with the gas supply tank by a valve. In order to regulate the heating the pipe coil is provided with a sensing device which responds to the presence of liquified gas and which operates on the valve which is mounted on the gas heater supply pipe.

These vaporizers have the disadvantage of utilizing a considerable part of the gas intended for the heating device for the purpose of heating the gas particularly during cold outside temperatures. Moreover, the control circuit for the gas heating is frequently damaged because of shaking and vibrations which occur at the framework during operation of the machine.

SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide an apparatus which will avoid the above drawbacks.

In particular, it is an object of the present invention to provide a pavement-removing apparatus, to be used in connection with highway repair, which is capable of having that part of the apparatus which heats. the pavement prior to removal thereof either extended into an operative position extending forwardly from a vehicle of the apparatus or retracted to an inoperative position where it can conveniently be carried by the vehicle during travel of the apparatus from one job to another, for example.

Thus, it is an object of the invention to provide an apparatus of this type which does not require any additional vehicles in order to transport the apparatus from one location to another.

It is also an object of the present invention to provide an apparatus of this type which permits the available sources of energy such as a suitable fuel used for heating purposes to be used in a high efficient manner.

Also, it is an object of the present invention to provide an apparatus which can have its operation adjusted in such a way that the operation of the apparatus can be adapted to the existing conditions which are encountered at a given location.

In addition, it is an object of the present invention to provide an apparatus of the above type which if it does not have the heating structure collapsed to a location carried by the vehicle can pull the heating structure with the latter rolling along the highway and adapting itself automatically to curves in the highway without any problems.

Thus, it is an object of the present invention to provide an apparatus of the above type which enables the heating structure to be steered by an operator of the vehicle.

In addition, it is an object of the present invention to provide an exceedingly efficient apparatus capable of taking advantage of heat sources, such as heat radiating from the pavement itself, in order to reduce the heating requirements for purposes such as vaporizing a liquified gas into a dry form.

Furthermore, it is an object of the present invention to provide an apparatus of the above type which is exceedingly simple and inexpensive while at the same time being highly efficient and highly effective in achieving the desired results, with a considerable part of the apparatus lending itself to automatic operation by including suitable sensors and the like which respond to variable factors in order to provide automatic controls in a highly effective manner.

According to the invention the pavement-removing apparatus which is to be used in connection with highway repair includes a vehicle which is adapted to travel on a highway. A frame means is removably connected to and extends from the front end of the vehicle, this frame means including a plurality of relatively flat sections. A suitable means connects these sections to each other for movement with respect to each other between an inoperative position where the sections are respectively located in planes located one directly next to the other and inoperative position where the sections are located substantially in a common plane extending forwardly from the vehicle. A radiating means is carried by these sections for radiating heat downwardly toward the pavement preparatory to removal thereof, when the sections are in their operative position. This radiating means consumes gas in order to provide the radiant heat, and a gas-supply means communicates with the radiating means for supply to the latter gas to be consumed thereby for providing the radiant heat.

BRIEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the I FIG. 2 is a fragmentary top plan view of the apparatus of FIG. 1;

FIG. 3 is a schematic elevation of another embodiment of an apparatus according to the invention;

FIG. 4 is a fragmentary top plan view of the apparatus of FIG. 3;

FIG. 5 is a fragmentary schematic elevation of a further embodiment of an apparatus according to the invention; and

FIG. 6 is a transverse sectional elevation taken along line IIII of FIG. 5 in the direction of the arrows and showing details of a vaporizing means.

DESCRIPTION OF PREFERRED EMBODIMENTS The apparatus for cutting pavement according to FIGS. 1 and 2 consists, as is particulary apparent from FIG. 1, of a vehicle chassis 1, having a pair of longitudinally extending side beams 2 and 3 the front end regions of which are illustrated and also having the front wheels 4. At the rear portion of the vehicle chassis are the driving engine, in general a Diesel engine, and the station for the operator. The longitudinal beams 2 and 3 fixedly carry holders 6 to which a pair of holding arms 7 are pivoted, these arms 7 serving as bearings for the cutting roller 8 and its shaft 9. On the shaft 9 of the cutting roller is a sprocket wheel 10 which by way of a sprocket chain 11 is connected directly or indirectly through a transmission to the driving engine. In order to adjust the elevation of the cutting roller 8 there is a hydraulic piston drive 12 which is controlled from the operators station.

A supporting frame 13 is welded to the ends of the longitudinal beams 2 and 3 which are adjacent the front wheels, and a platform 14 is bolted to the supporting frame 13. The platform 14 carries at its end which is distant from the chassis 1 a coupling arm 15 to which heating apparatus 16 is swingably connected.

The heating apparatus 16 includes a frame 19 made of a pair of parts 17 and 18 and which is supported by supporting Wheels 20 on the highway surface 21 which is to be cut away. The pair of parts 17 and 18 of the frame 19 are swingably connected to each other along an axis 22 which extends transversely to the direction of travel. The frame part 17 is in addition connected, at its other end, to a carrier 24 for swinging movement about an axis 23 which is parallel to the axis 22. The carrier 24 carries at its side which is distant from the swing axis 23 a coupling arm 25. This coupling arm and the coupling arm 15 which is carried by the platform 14 are connected to each other by way of a coupling pin 26.

The extending of the heating apparatus 16 and the contraction of both frame parts 17 and 18 at the front portion of the vehicle chassis l, as well as the guiding of the heating apparatus along curves, are brought about by way of apair of hydraulic piston drives 27 and 28 on the platform 14. These piston drives respectively have piston rods 29 and 30 swingably connected to the frame part 17 by way of connecting links 31 and 32, respectively. By loading both piston drives respectively with different pressures of the pressure medium, the heating apparatus can be swung horizontally to some extent, with the supporting wheels 20, the shafts of which are carried by vertically extending components 33 which are connected to the frame 19 for turning about vertical axes, respectively, being capable of adapting themselves to the direction of movement of the frame 19. By an equal loading of both hydraulic piston drives 27 and 28 with the pressure medium, the frame 19 can be extended outwardly away from the chassis frame 1 or can be contracted or retracted back to the front part of the chassis framel. On the platform 14 are, moreover, several gas tanks 34 which form the source of energy for the heating apparatus 16, these tanks 34 communicating with a pipe system 36, which is fixed to the frame 19, by way of a single flexible hose 35 or a plurality of flexible hoses. The pipe system 36 is composed of several pipe sections which form the heating elementsand which are curved into a meander configuration and provided with a series of gas discharge openings only the pipe sections 360 and part of the pipe section 36b being illustrated for the sake of clarity of illustration these pipe sections being connected to each other at the regions of the swing axes 22 and 23 by flexible hose sections 37.

The supporting wheels are preferably adjustable in elevation by way of suitable screw spindle drives or the like, so that the distance of the burner from the highway surface can be adjusted and thus the extent of heating can be regulated to some extent in accordance with the requirements which are encountered. In particular, when the cutting operations are carried out during the winter months, this capability of adjusting the elevation of the burner has proved to be particularly advantageous.

According to another embodiment of the apparatus of the invention for cutting away pavement, which is illustrated in FIGS. 3 and 4, the machine includes 8. vehicle chassis 1 having a front pair of wheels 4, a rear pair of wheels 5, and driven by a Diesel engine 38. In addition, the machine includes a cutting device 8A for removing the worn or damaged highway covering 21. Over the Diesel engine 38 is located the operator station 40 of the machine. Behind the operator station 40 extends the exhaust pipe 41 of the Diesel engine 38 from the engine cover 42.

The cutting apparatus 8A includes a rotary cutting roller 8 which turns in a direction opposite to the direction of travel indicated by the arrow A, this cutting roller S'being rotatably carried by a pair of arms 43 which are swingably connected to the vehicle chassis l, and the roller 8 is driven by a chain drive 44 which is operatively connected to the Diesel engine 38 by a transmission which includes the drive shaft 45. In order to adjust the elevation of the cutting roller 8, each of the swingable arms 43 is operatively connected 'with a pneumatic or hydraulic servomotor 46.

The vehicle chassis l is provided at its front part with 57. As already pointed out, it is necessary to supply heat energy to the vaporizer 53 in order to achieve a combustible dry gas from the liquified gas 50. With this embodiment this operation takes place by Way of a gas heater 58 which communicates by way of a pipe 59 and a valve 60 with the upper interior space of the container 48 which contains dry gas 61. The vaporizer 53 can be situated at the lower side of the trough 47 instead of at the front side of the vehicle chassis 1, which provivdes the advantage that the heat radiation given up by the heated highway surface 21 acts as an additional heater and the use of dry gas for heating the vaporizer 53 can be reduced.

In order to measure the amount of liquified gas which is present in the large container 48 there is a pneumatic measuring device 62 for measuring the level of the liquified gas,this measuring device 62 being connected by a fluid-pressure pipe or an electrical conductor in accordance with the construction of the signaltransmitter to an unillustrated indicating instrument situated at-the operator station. The connection 63 between the signal transmitter and the indicating instrument of the measuring device is indicated.

The heating apparatus 57 consists of at least a pair of frame parts 64 and 65 which are swingably connected to each other and of which the frame parts 65 which is adjacent the vehicle chassis 1 of the machine has one part of a coupling 66 by which the heating apparatus is turnably connected with the vehicle chassis l where the other part of the coupling is situated. The heating apparatus 57 is provided with a plurality of supporting wheels or rollers 20 by which it is supported on the pavement 21 which is to be cut away. The steering of the heating apparatus 57 takes place by way of a pneumatic or hydraulic servomotor 68 whose push rod 69 is fixed to the frame part 65. The construction of the heating apparatus 57 with two or more frame parts 64 and 65 which are swingably connected to each other has the advantage which has already been set forth above in detail that the heating apparatus or at least a substantial part thereof can be swung upwardly which particulary during pure travelling of the vehicle, when the machine is driven to its place of use, considerably a trough 47 in which a cylindrical large gas tank 48 is I The vaporizer 53 is made up of a pipe coil 54 which has a plurality of windings and which is connected at one end to a shut-off valve 55. Subsequent to the shutoff valve there is a pressure-reducing valve 56 the outlet of which is connected with the heating apparatus simplifies the transportation of the machine. The swinging of the heating apparatus 57 either upwardly or downwardly can take place manually or by way of an unillustrated additional servomotor.

On the frame parts 64 and 65 which are pivotally connected to each other there are one or more heating coils 70 which form different heating zones, each of these heating coils 70 having a plurality of gasdischarge bores. When the heating coils 70 form a plurality of different heating zones, there is provided subsequent to the pressure-reducing valve 56, which advantageously is controlled by a heat sensor 71 which responds to the heating of the pavement 21, an unillustrated switching device which connects one, a plurality, of all of the heating coils to the pressure reducing valve 56.

In order to increase the efficiency of the vaporizer 53 and heat 58 which form the vaporizing system the vaporizer 53 is provided with a sensor 73 which responds to the presence of liquified gas, which is located at the first third of the vaporizing pipe coil 54 and which serves to control the heater 58.

In a further example of an embodiment of the machine of the invention for cutting away pavement,

which is illustrated in FIGS. and 6, this machine for cutting away pavement includes a vehicle chassis I having a pair of longitudinal beams 3, the front ends of which are illustrated and front wheels 4. On the unillustrated rear part of the vehicle chassis l are the driving engine, the operator stand, and the large gas container. A pair of holding arms 7 are pivotally connected with holders 6 which are fixed to the longitudinal beams 3, these arms 7 serving to support for rotary movement the cutting roller 8 with its shaft 9. Furthermore, the shaft 9 carries a sprocket wheel 10 which by way of a sprocket chain 11 is connected directly or indirectly through a transmission with the driving engine. To adjust the elevation of the cutting roller 8 there is a hydraulic piston drive 12 whose push rod 12A is pivotally connected to a holding arm 7, this piston drive 12 being actuated from the operator station.

A carrier frame 13 with a coupling pin 15A is welded to the ends of the longitudinal beams 3 which are adjacent the front wheels 4, and the rear end of the heating apparatus 16 is hung onto the coupling pin 15A.

The heating apparatus 16 includes frame 19 which is composed of two parts 17 and 18 and which is supported at its front end by a pair of supporting wheels 20 on the pavement 21 which is to be cut away. Both of the parts 17 and 18 of the frame 19 are connected to each other for swinging movement about the axis 22 which extends transversely to the travelling direction. The frame part 17 is, furthermore, connected at its other end to a carrier 24 for swinging movement about axis 23 which is parallel to the axis 22, the carrier 24 having the construction ofa coupling. To the lower side ofthe frame 19 are connected a plurality of heating elements 74 constructed as infrared radiating devices. The heating elements 74 are connected to each other by way of hoses 7S and by way ofa hose 76 to the vaporizer 77 which in turn is in communication with the unillustrated large gas container by way of a hose 78.

The vaporizer 77 rests on a holder 79 which at one end is supported for swinging movement aboutthe axis 81 by a pair of carriers 80 which are spaced from each other. The carriers 80 are in turn welded to the frame part 17. The free ends ofthe carriers 80 support a shaft 82 on which a guide roller 83 for a cable 84 is supported for free rotary movement, one end of the cable 84 being connected to a hook 85 carried by the holder 79. The other end of the cable 84 is wound onto a drum 87 supported for rotary movement between a pair of side plates 86 which are welded to the carriers 80. The drum 87 is fixed to the shaft 88 which carries the hand crank 89.

The vaporizer can, as shown in the drawing, extend along the entire length of the heating apparatus. As a rule, however, it is sufficient for the required vaporizing output if the vaporizer extends only up to the swing axis 22 between the pair of frame parts 17 and 18 ofthe heating apparatus. This has then also the advantage that the vaporizer can be swung up together with the heating apparatus.

As is particularly apparent from FIG. 6, the holder 90 includes a frame having a pair of longitudinal carriers 90 of U-shaped cross section which are connected to each other at one end by a transverse carrier 91. The vaporizer 77 is fixed to the upper walls 92 of both carriers 90 while the lower walls 93 serve as guide surfaces for a plurality of flat plates 94.

Each of these plates 94 is made of a pair of layers 95 and 96 of which the lower is aluminum and the upper asbestos. The plates 94 are connected to each other along their longitudinal edges 97 which extend transversely to the direction of travel of the vehicle in the manner of the elements of the roll top of a roll top desk, and these plates 94 can be rolled onto and unrolled from a shaft 98 supported for rotary movement by both carriers 80. In order to roll up and unroll the plates the shaft 98 fixedly carries a hand crank 99.

Thus, with the embodiment of FIGS. 5 and 6 it is possible by turning the crank 99 for the operator to adjustably block the space between the vaporizing means 77 and the radiating means 74 so that the vaporizer 77 can receive a given amount of heat not only by way of heat which escapes upwardly from the radiating means 74, but also by way of heat which is reflected upwardly from the highway 21. In addition, the lower reflecting surface of the plate means 94 will be capable of directing back to the road any heat which tends to rise upwardly. Thus an exceedingly efficient operation is achieved with this embodiment.

Thus, the objects of the invention are achieved by providing a heating device with gas-heated radiating devices which are carried by a framework supported wheels and being swingable in front of the vehicle chassis, these radiating devices being in communication with one or more liquified gas containers with, in some cases, one or more Vaporizers being connected between the liquified gas containers and the radiating devices.

According to a further advantageous feature the heating device which consists of the gas-heated radiating devices is carried by a frame which is situated in front of the vehicle chassis and supported on wheels, with the frame being made of a pair of parts which are swingable With respect to each other about a first approximately horizontal axis extending transversely of the direction of travel and of which one is swingably connected directly or indirectly to the front of the vehicle for movement about an axis which is parallel to the first axis, with means being provided to swing both parts of the frame.

With the structure of the invention the heating device remains at the vehicle chassis and after termination of the cutting or stripping operations is swung up to and on to the front part of the vehicle frame, so that the heating structure is not disturbed during transportation operations along. As a result the inconvenient and time-consuming mounting and dismounting of the heating device before and after cutting operations are eliminated, and with elimination of the latter operations there is also an elimination of the connecting and disconnecting operations between the energy source and heating elements. In addition, no further transporting means are required.

The expansion of the heating structure and the contraction of both frame parts at the front side of the apparatus can take place manually, for example by way of a winch actuated by the operator. Also, there is a possibility of expanding and contracting both frame parts with a motor whose shaft is connected to a trans mission for example in the form of a winch. Swinging of both frame parts at least with one hydraulic piston drive has proved to be particularly favorable, since in general there are in any event hydraulic installation available for adjusting the elevation of the cutting or stripping structure, so that the piston drive can be connected to such hydraulic installations;

In order to guarantee that the wheels which are connected to the frame of the heating structure can adapt themselves to curves of the highways, it is preferably to arrange each supporting wheel in a journal which supports each wheel at the frame for turning about a substantially vertical axis. In this way it is assured that the supporting wheels can always adapt themselves to the particular direction of movement and are not shoved transversely to their direction of rotation on the pavement, which could result in damaging the pavement and/or the supporting wheels and bearings. A further improvement for the guiding of the heating structure can be achieved by connecting the part of the frame adjacent the front of the vehicle swingably to a carrier which is swingably connected directly or indirectly to the chassis for swinging movement about a substantially vertical axis and controlling the frame with a pair of hydraulic piston drives. In this way, by providing different hydraulic loads on the piston drives with the pressure medium there is the posibility of being able to steer the frame to some extent, while with equal pressures of the hydraulic pressure medium at both piston drives the frame can be extended or retracted at the front of the vehicle chassis.

Since it does not infrequently happen that the heating structure is not required for the cutting or stripping part of the apparatus and therefore can be dismounted from one vehicle and connected to another, it is preferably to provide a platform for receiving the energy source for the heating elements and the means for swinging both frame parts, such as, for example, one or more hydraulic piston drives, with the frame being swingably connected to such a platform and with the platform being disconnectable from the front side of the vehicle chassis. Such a construction makes it possible by disconnecting only a few screw connections to remove the entire heating apparatus from the chassis which carries the cutting or stripping structure or from the chassis of the vehicle. As a result it is possible to avoid providing a heating apparatus for each cutting or stripping structure, which in particular in the case of a large number of machines works favorably in connection with purchasing costs.

According to a further embodiment of the present invention, the heating structure is connected by way of a vaporizer to one or more large containers for liquified gas. In this way there is a substantial simplification in the manufacturing and operation of the heating device. Thus, there is an elimination of the large time and labor costs involved in exchange of gas tanks, since the single tank for the liquified gas can be filled from a single supply tank car. Such filling can take place during operation of the machine, if it is seen that the liquified gas tank or tanks are respectively provided with an additional filling pipe which can be separately closed. Inasmuch as each tank in any event has only two connections, namely one for filling the tank and the other for discharge of liquified gas, of which, again, only the filling connection is actuated more often, there will be almost no leakage losses. Moreover, it is possible in this way to do without a large number of pipe coils and to reduce the communicating system between the one or more large tanks and the heating apparatus to a single pipe system. This reduces the manufacturing costs of the heating structure of the invention as contrasted with the known structure to a not inconsiderable extent.

In general only a single large tank is provided for the liquified gas and only in special cases when, for example, there is no large continuous supporting surface for a single large tank, will two or more tanks be used. The large tanks can have a spherical or cylindrical configuration, although the cylindrical tank is preferred because of the better use of available space.

According to a preferred embodiment the large tanks for the liquified gas are arranged on the chassis of the machine. However, there is also the possibility to mount the liquified gas tanks beneath its own vehicle chassis which can be coupled to the vehicle chassis of the apparatus. In this case, however, it should be seen that for one or more machines an additional liquified gas tank chassis is present if continuous supply for the heating apparatus is to be assured. On the other hand, the capability of connecting a gas tank vehicle chassis to the vehicle chassis of the machine provides certain advantages with respect to one or more gas tanks mounted on the vehicle of the machine itself, these advantages being present with respect to assurance of operation so that from one case to the next it will be decided which of these arrangements should be used. In order to avoid obstructing the view of the machine operator with an arrangement of one or more gas tanks on the chassis of the machine, it is preferred to situate the gas tank or tanks in a trough of the vehicle chassis. A cylindrical gas tank is preferably arranged in such a trough with its longitudinal axis extending transversely to the direction of travel in order to achieve the best possible use of the available space. Finally for proper operation of the machine use should be made of a gauge which indicates the extent to which the tank is filled. It is particularly desirable to use pneumatically or electrically operating measuring devices, since with such devices it is possible to situate an indicating instructment in the cab of the machine without any difficulty and thus to inform the machine operator at all times during the operation of the machine about the extend to which the tank or tanks are filled.

The vaporizers which are connected with the tank or tanks can have a conventional construction. To achieve a combustible dry gas from the liquified gas the vaporizer must be heated, as is known. This can take place by heating the vaporizer with heat supplied from the exhaust gases of the engine. In this way the heat energy of the exhaust gas is used and an additional source of energy is not required. Another desirable way to heat the vaporizer is to provide the vaporizer with a gas heater which communicates through a pipe, which carries a valve, with the upper interior part of the gas tank. Of course, in this latter case a part of the gas intended for the heating apparatus is consumed. This part is however relatively small and can be rendered even smaller if the vaporizer is situated at the front part of the chassis of the machine adjacent the level of the road so that it is exposed to the heat from the highway surface. Such an arrangement of the vaporizer is also desirable in the case where the vaporizer is provided with heat energy from the exhaust gas of the driving engine. In this case an additional heating of the vaporizer is derived from the heated pavement, which is of advantage when the surrounding temperature is low. To increase the efficiency of the vaporizing system it is preferred to provide the vaporizer with a control which responds to the presence of liquified gas for controlling the heating of the vaporizer.

It is most preferred to situate between the vaporizer and the heating apparatus a shut-off valve so that it is possible to prevent the supply of dry gas when required. Moreover, it is preferred to situate subsequent to the vaporizer or the shut-off valve a pressure-reducing valve which makes it possible to adjust the supply of dry gas to the heating structure in accordance with the desired heating of the pavement. Of course, such an adjustment can also take place by controlling the heating of the vaporizer, but such an arrangement is more complicated. The adjustment of the heating apparatus to achieve a predetermined heating of the pavement by way of supplying a given amount of dry gas per unit of time can be brought about by manual control of the pressure-reducing valve or, which is of particular advantage, in such a way that the pressure reducing valve is controlled by a heat-sensor which responds to the heating of the pavement.

For the structure of the heating apparatus itself it is possible to use a conventional construction. However, it has proved to be particularly desirable to use a heating apparatus which is divided into several heating zones which are separate from each other and which can be selectively connected to the pipe leading from the vaporizer or the shut-off valve and/or pressurereducing valve. This arrangement provides the advantage of being able to change the area to be heated within wide limits.

According to a further advantageous feature of the present invention the vaporizer is situated over the heating apparatus and means are provided for controlling the energy of the heat radiation from the heating apparatus and the heated pavement which operates on the exterior surface of the vaporizer. In this way the heat from the heating apparatus and its surroundings and from the pavement is utilized for heating the vaporizer. By way of this use of radiating heat energy which during operation of the heating apparatus is always available it is possible to avoid completely the use of any additional vaporizer heaters. This operates advantageously not only with respect to manufacturing costs but also with respect to operating costs of the structure, since the liquified gas can in this case be used exclusively for heating the highway pavement. Since moreover it is possible to use, for controlling the radiating heat energy means such as, for example, metal reflectors, which are capable of meeting the operating requirements, the solution to the problem provided by the present invention is proper for the requirements which are encountered.

Taking into consideration the fact that the radiant heat given up from the heated pavement will initially be somewhat weakened by the layer of air situated between the pavement and the vaporizer, it is preferred to use a vaporizer having a large surface area. Thus, it is preferred to use a vaporizer whose effective area which is directed toward the pavement is relatively large. Since such a vaporizer in general, however, has a large gas-receiving volume, it is possible for large gas losses to occur if during cutting or stripping of certain pavements the heating apparatus and vaporizer are not required and thus in this case are uncoupled from the machine, which is undesirable. This can be avoided with a vaporizer having at least one pipe coil of a meandering configuration, a construction which is conventionally used, by providing the pipe which is of a material having good thermal conductivity with an inner diameter which is substantially smaller than its outer diameter. A vaporizer with such a pipe will have a large effective surface area with a relatively small gas volume.

In order to influence the radiating heat energy which acts on the exterior surface of the vaporizer, it is preferably to situate between the vaporizer and the heating apparatus at least one shiftable or swingable heatinsulating and/or reflecting plate. In this way the effective exterior surface of the vaporizer can be covered with respect to the heat radiation by increasing or decreasing the extent of shifting or swinging of the plate or plates, to achieve a partial or complete covering with respect to the heat radiation and as a result to be capable of controlling the heat of the vaporizer within wide limits. in addition to the latter or in place thereof it is possible to arrange over the vaporizer at least one shiftable or swingable heat-insulating and/or reflecting plate. By way of such a plate arrangement it is possible to achieve a build-up of heat in the region of the vaporizer, with the intensity of the heat permitting itself to be controlled by corresponding shifting or swinging of the plate or plates.

Particularly with respect to a simple manipulation of the structure it has proved to be desirable to provide a plurality of heat-insulating and/or reflecting plates. These plates can be made either of metal, such as, for example, aluminum, or a heat-insulating material such as, for example, asbestos, or, as is particularly desirable with respect to mounting techniques, from a pair of layers of these materials which are connected to each other, thus, for example, from aluminum and asbestos plates which are joined to each other.

Since swingable plates, with respect to their manipulation and their space requirements are in general somewhat less desirable than shiftable plates, the latter is preferred. Moreover, it is possible to provide with shiftable plates a construction which is particularly simple to manipulate. Such a construction has in accordance with a further feature of the invention the individual plates connected to each other in the manner of a roll top, as encountered with desks, and these plates can be rolled up onto and unrolled from a shaft which extends transversely to the direction of travel. The rolling and unrolling of these plates can be carried out manually by way of a crank which is fixed to the shaft or by way of a motor such as a hydraulic or electric motor. A further advantageous feature resides in connecting the individual plates to each other at their ends which are directed toward the heating apparatus, provided that the plates are capable of being gathered together into one group in response to one operating stroke while on the other hand they can be spread apart from each other to form a covering surface similar to overlapping roof shingles.

According to a further advantageous feature of the invention the covering medium can also have the form of the top of a roll top desk and be shiftable in guides located at its edges to a considerable distance over or under the heating apparatus so as to achieve a control with the same effective amount of heat.

According to another embodiment of the invention the covering elements can have a jalousie arrangement in which the mutually overlapping covering strips are adjustable with respect to each other in a manner similar to a Venetian blind, so that in this way the size of the passages for the heated air can be regulated.

The control of the radiant. heat energy which operates from the heating apparatus and the heated pavement on the exterior surface of the vaporizer can, according to a further feature of the invention, also be provided by connecting the vaporizer swingably to the heating apparatus. The control is brought about with this arrangement by the change in the distance between the effective exterior surface of the vaporizer and the heated pavement or heating apparatus and the resulting increase or decrease in the volume of air between the vaporizer exterior surface, on the one hand and the pavement and heating apparatus, on the other hand, which weakens the heat radiation.

The swinging of the vaporizer can take place in a direction parallel to its four peripheral edges. It is best, however, to provide a swinging axis which is parallel or almost parallel to the pavement and transverse to the direction of travel, this swinging axis being situated at the region of the rear end of the heating apparatus. The swinging of the vaporizer aobut such an axis is particularly of advantage when an upwardly swingable heating apparatus is used. Such a heating apparatus is, after termination of the cutting or stripping operations, swung up and onto the front part of the vehicle chassis, so that it is not disturbed during transportation alone. in this way it is possible to eliminate the inconvenient and time-consuming mounting and dismounting of the heating apparatus before and after the cutting operations, and thus it is also possible to eliminate operations in connection with providing and removing connections between the energy source and the heating apparatus, as are encountered with heating apparatus which cannot be swung up to an inoperative position.

In order to swing the vaporizer it is preferred to use a winch. However, instead of a winch and cable construction it is also possible to use a hydraulic servomotor.

According to a further advantageous embodiment of the invention, which is particularly effective with respect to the difficult operating conditions which are encountered, the swinging of the vaporizer is brought about by way of a rack jack which operates between the burner frame and the front edge of the vaporizer.

It is to be noted in this connection that the control of the radiant heat energy which acts on the exterior surface of the vaporizer is brought about either by a swingable arrangement of the vaporizer or by providing an arrangement of one or more swingable or shiftable these plates are connected to each other in the manner of the elements of a rolltop of a desk, a construction is preferred where the holder for the vaporizer has a frame with a pair of elongated channel-shaped beams, these channel beams of U-shaped profile having upper walls fixed to the vaporizer and lower walls acting as guide surfaces for the individual plates. What is claimed is: I

l. in a pavement-removing apparatus to be used in connection with highway repair, a vehicle adapted to travel on a highway, frame means removably connected to and extending from the front end of the vehicle, said frame means including a plurality of relatively flat sections, means connecting said sections to each other for movement with respect to each other between an inoperative position where said sections are respectively located in planes located one directly next to the other and an operative position where said sections are located substantially in a common plane extending forwardly from the vehicle, radiating means carried by said sections for radiating heat downwardly toward pavement preparatory to removal thereof when said sections are in said operative position, said radiating means consuming gas to provide the radiant heat, and gas-supply means communicating with said radiating means for supplying to the latter gas to be consumed thereby for providing the radiant heat.

2. The combination of claim 1 and wherein said sections are hingedly connected to each other.

3. The combination of claim 2 and wherein said radiating means includes elongated tubes distributed over said sections and formed with bores which are directed downwardly when said sections are in their operative position, said gas-supply means supplying to said tubes a combustible gas for providing flames directed downwardly from said tubes toward the pavement when said sections are in their operative position.

4. The combination of claim l and wherein said radiating means includes a plurality of infrared radiating devices consuming gas to provide the infrared heat radiation.

5. The combination of claim 1 and wherein said gas supply means includes tanks of dry gas communicating with said radiating means for supplying to the latter gas to be consumed during provision of heat radiation.

6. The combination of claim 1 and wherein said gassupply means includes a tank containing liquified gas and a vaporizing means communicating with said tank for converting the liquified gas into dry gas, said vaporizing means communicating with said radiating means for supplying to the latter dry gas to be consumed during provision of radiant heat.

7. The combination of claim 1 and wherein said frame means includes two sections connected to each other by said connecting means for swinging movement realtive to each other about a first axis extending substantially horizontallyand transversely with respect to the direction of travel of the vehicle, and one of said sections being connected to said vehicle for swinging movement with respect thereto about a second axis which is parallel to the first axis, and means operatively connected to at least one of said sections for swinging said sections with respect to said axes.

8. The combination of claim 7 and wherein said means for swinging of said sections is a hydraulic means.

9. The combination of claim 1 and wherein a wheel means supports said frame means for movement along a highway together with the vehicle, said wheel means including a plurality of wheels and a plurality of posts extending upwardly from said wheels and supporting the latter for rotary movement, said posts being operatively connected with said frame means, at at least one of said sections thereof, for turning movement about vertical axes, respectively, so that the wheels can orient themselves automatically during negotiation of turns.

10. The combination of claim 1 and wherein said frame means includes a carrier section directly connected to the vehicle for swinging movement with respect thereto about a vertical axis, and at least one additional section swingably connected to said carrier section by said connecting means at an end of said carrier section distant from the vehicle, and hydraulic means operatively connected to said frame means for moving the latter between said operative and inoperative positions.

11. The combination of claim 1 and wherein said vehicle includes at its fron end a platform to which said frame means is connected, said gas-supply means being carried by said platform, and the latter being removably connected to a chassis of the vehicle at the front end region of the latter.

12. The combination of claim 1 and wherein an 'adjusting means is operatively connected with said frame means for adjusting the distance thereof from a highway surface.

13. The combination of claim 12 and wherein a wheel means supports said frame means for movement together with the vehicle, said wheel means including wheels and posts extending upwardly from said wheels to said frame means, and an adjustable screw-spindle drive connected between said wheels and posts for adjusting the elevation of said frame means with respect to the highway surface.

14. The combination of claim 6 and wherein said tank of liquified gas is carried by said vehicle.

15. The combination of claim 14 and wherein said vehicle has a trough in which said tank is located.

16. The combination of claim 15 and wherein said tank is of a cylindrical configuration and has a central axis extending horizontally across the vehicle transversely to the direction of travel thereof.

17. The combination of claim 6 and wherein said tank is carried by a separate vehicle which can be coupled to the vehicle to which the frame means is connected.

18. The combination of claim 6 and wherein a measuring means is provided for indicating the extent to which the tank is filled with liquified gas.

19. The combination of claim 6 and wherein a shutoff valve means is located between said vaporizing means and said radiating means for providing or cutting off communication between said vaporizing means and said radiating means.

20. The combination of claim 19 and wherein a pressure-reducing valve means is connected between said shut-off valve and said radiating means.

21. The combination of claim 20 and wherein a sensor means for responding to heat radiating from the pavement is operatively connected with said pressurereducing valve means for controlling the latter automatically.

22. The combination of claim 6 and wherein said radiating means includes a plurality of sections which can be selectively connected either separately or together to said vaporizing means.

23. The combination of claim 6 and wherein said vaporizing means is located at a front portion of the vehicle adjacent the pavement.

24. The combination of claim 6 and wherein said vaporizing means includes a gas heater communicating 26. The combination of claim 6 and wherein a heating means operatively connected with said vaporizing means for heating the latter, said vaporizing means including a sensor which responds to the presence of liquified gas, said sensor being operatively connected with said heating means for controlling the operation thereof in accordance with detection of liquified gas by said sensor.

27. The combination of claim 6 and wherein said vaporizing means is situated over said radiating means to receive some heat from said radiating means as well as some heat from the heated pavement itself, and adjusting means coacting with said vaporizing means for adjusting the extent to which the latter receives heat from said radiating means and from the pavement.

28. The combination of claim 27 and wherein said vaporizing means has a flat configuration and is distributed over a relatively large area.

29. The combination of claim 6 and wherein said vaporizing means includes at least one pipe coil of a meandering configuration composed of a pipe made of a material of good thermoconductivity and having an internal diameter which is substantially smaller than its outer diameter.

30. The combination of claim 6 and wherein said vaporizing means is swingably connected to said radiating means.

31. The combination of claim 30 and wherein said vaporizing means is swingable about an axis which is approximately horizontal and extends transversely to the direction of travel of the vehicle.

32. The combination of claim 30 and wherein a winch means is operatively connected with said vaporizing means for swinging the latter.

33. The combination of claim 30 and wherein a hydraulic servomotor is operatively connected to said vaporizing means for swinging the latter.

34. The combination of claim 30 and wherein at least one heat-insulating and reflecting plate means is situated between said vaporizing means and said radiating means and is movable in the space between said vaporizing means and radiating means.

35. The combination of claim 30 and wherein a heatinsulating and reflecting plate means is movably situated over said vaporizing means.

36. The combination of claim 34 and wherein said plate means includes a plurality of separate plates connected to each other.

37. The combination of claim 36 and wherein said separate plates are hingedly connected to each other to act in the manner of a rolltop of a rolltop desk.

38. The combination of claim 36 and wherein said plates are connected to each other for collapse into one group in response to one operating stroke and for spreading apart into an operative position also in response to one stroke said plates having in their operative position an arrangement of overlapping roof shingles.

39. The combination of claim 28 and wherein a pair 40. The combination of claim 34 and wherein said of elongated channels of U-shaped profile have upper heat-insulating and reflecting plate means includes two walls fixed to and carrying said vaporizing means while layers one of which is metal and the other of which is heat-insulating and reflecting plates are shiftable within of a heat-insulating material. said channels. 

1. In a pavement-removing apparatus to be used in connection with highway repair, a vehicle adapted to travel on a highway, frame means removably connected to and extending from the front end of the vehicle, said frame means including a plurality of relatively flat sections, means connecting said sections to each other for movement with respect to each other between an inoperative position where said sections are respectively located in planes located one directly next to the other and an operative position where said sections are located substantially in a common plane extending forwardly from the vehicle, radiating means carried by said sections for radiating heat downwardly toward pavement preparatory to removal thereof when said sections are in said operative position, said radiating means consuming gas to provide the radiant heat, and gas-supply means communicating with said radiating means for supplying to the latter gas to be consumed thereby for providing the radiant heat.
 2. The combination of claim 1 and wherein said sections are hingedly connected to each other.
 3. The combination of claim 2 and wherein said radiating means includes elongated tubes distributed over said sections and formed with bores which are directed downwardly when said sections are in their operative posItion, said gas-supply means supplying to said tubes a combustible gas for providing flames directed downwardly from said tubes toward the pavement when said sections are in their operative position.
 4. The combination of claim 1 and wherein said radiating means includes a plurality of infrared radiating devices consuming gas to provide the infrared heat radiation.
 5. The combination of claim 1 and wherein said gas supply means includes tanks of dry gas communicating with said radiating means for supplying to the latter gas to be consumed during provision of heat radiation.
 6. The combination of claim 1 and wherein said gas-supply means includes a tank containing liquified gas and a vaporizing means communicating with said tank for converting the liquified gas into dry gas, said vaporizing means communicating with said radiating means for supplying to the latter dry gas to be consumed during provision of radiant heat.
 7. The combination of claim 1 and wherein said frame means includes two sections connected to each other by said connecting means for swinging movement realtive to each other about a first axis extending substantially horizontally and transversely with respect to the direction of travel of the vehicle, and one of said sections being connected to said vehicle for swinging movement with respect thereto about a second axis which is parallel to the first axis, and means operatively connected to at least one of said sections for swinging said sections with respect to said axes.
 8. The combination of claim 7 and wherein said means for swinging of said sections is a hydraulic means.
 9. The combination of claim 1 and wherein a wheel means supports said frame means for movement along a highway together with the vehicle, said wheel means including a plurality of wheels and a plurality of posts extending upwardly from said wheels and supporting the latter for rotary movement, said posts being operatively connected with said frame means, at at least one of said sections thereof, for turning movement about vertical axes, respectively, so that the wheels can orient themselves automatically during negotiation of turns.
 10. The combination of claim 1 and wherein said frame means includes a carrier section directly connected to the vehicle for swinging movement with respect thereto about a vertical axis, and at least one additional section swingably connected to said carrier section by said connecting means at an end of said carrier section distant from the vehicle, and hydraulic means operatively connected to said frame means for moving the latter between said operative and inoperative positions.
 11. The combination of claim 1 and wherein said vehicle includes at its fron end a platform to which said frame means is connected, said gas-supply means being carried by said platform, and the latter being removably connected to a chassis of the vehicle at the front end region of the latter.
 12. The combination of claim 1 and wherein an adjusting means is operatively connected with said frame means for adjusting the distance thereof from a highway surface.
 13. The combination of claim 12 and wherein a wheel means supports said frame means for movement together with the vehicle, said wheel means including wheels and posts extending upwardly from said wheels to said frame means, and an adjustable screw-spindle drive connected between said wheels and posts for adjusting the elevation of said frame means with respect to the highway surface.
 14. The combination of claim 6 and wherein said tank of liquified gas is carried by said vehicle.
 15. The combination of claim 14 and wherein said vehicle has a trough in which said tank is located.
 16. The combination of claim 15 and wherein said tank is of a cylindrical configuration and has a central axis extending horizontally across the vehicle transversely to the direction of travel thereof.
 17. The combination of claim 6 and wherein said tank is carried by a separate vehicle which can be coupled to the Vehicle to which the frame means is connected.
 18. The combination of claim 6 and wherein a measuring means is provided for indicating the extent to which the tank is filled with liquified gas.
 19. The combination of claim 6 and wherein a shut-off valve means is located between said vaporizing means and said radiating means for providing or cutting off communication between said vaporizing means and said radiating means.
 20. The combination of claim 19 and wherein a pressure-reducing valve means is connected between said shut-off valve and said radiating means.
 21. The combination of claim 20 and wherein a sensor means for responding to heat radiating from the pavement is operatively connected with said pressure-reducing valve means for controlling the latter automatically.
 22. The combination of claim 6 and wherein said radiating means includes a plurality of sections which can be selectively connected either separately or together to said vaporizing means.
 23. The combination of claim 6 and wherein said vaporizing means is located at a front portion of the vehicle adjacent the pavement.
 24. The combination of claim 6 and wherein said vaporizing means includes a gas heater communicating with said tank at an interior upper portion thereof above the liquified gas therein for utilizing dry gas above the liquified gas of the tank for heating said vaporizing means.
 25. The combination of claim 6 and wherein said vaporizing means is heated by exhaust gas from an engine, the latter engine being used to propel the vehicle.
 26. The combination of claim 6 and wherein a heating means operatively connected with said vaporizing means for heating the latter, said vaporizing means including a sensor which responds to the presence of liquified gas, said sensor being operatively connected with said heating means for controlling the operation thereof in accordance with detection of liquified gas by said sensor.
 27. The combination of claim 6 and wherein said vaporizing means is situated over said radiating means to receive some heat from said radiating means as well as some heat from the heated pavement itself, and adjusting means coacting with said vaporizing means for adjusting the extent to which the latter receives heat from said radiating means and from the pavement.
 28. The combination of claim 27 and wherein said vaporizing means has a flat configuration and is distributed over a relatively large area.
 29. The combination of claim 6 and wherein said vaporizing means includes at least one pipe coil of a meandering configuration composed of a pipe made of a material of good thermoconductivity and having an internal diameter which is substantially smaller than its outer diameter.
 30. The combination of claim 6 and wherein said vaporizing means is swingably connected to said radiating means.
 31. The combination of claim 30 and wherein said vaporizing means is swingable about an axis which is approximately horizontal and extends transversely to the direction of travel of the vehicle.
 32. The combination of claim 30 and wherein a winch means is operatively connected with said vaporizing means for swinging the latter.
 33. The combination of claim 30 and wherein a hydraulic servomotor is operatively connected to said vaporizing means for swinging the latter.
 34. The combination of claim 30 and wherein at least one heat-insulating and reflecting plate means is situated between said vaporizing means and said radiating means and is movable in the space between said vaporizing means and radiating means.
 35. The combination of claim 30 and wherein a heat-insulating and reflecting plate means is movably situated over said vaporizing means.
 36. The combination of claim 34 and wherein said plate means includes a plurality of separate plates connected to each other.
 37. The combination of claim 36 and wherein said separate plates are hingedly connected to each other to act in the manner of a rolltop of a rolltop desk.
 38. The combinAtion of claim 36 and wherein said plates are connected to each other for collapse into one group in response to one operating stroke and for spreading apart into an operative position also in response to one stroke said plates having in their operative position an arrangement of overlapping roof shingles.
 39. The combination of claim 28 and wherein a pair of elongated channels of U-shaped profile have upper walls fixed to and carrying said vaporizing means while heat-insulating and reflecting plates are shiftable within said channels.
 40. The combination of claim 34 and wherein said heat-insulating and reflecting plate means includes two layers one of which is metal and the other of which is of a heat-insulating material. 